It is well known that when an engine of an automobile is not able to be started due to insufficient electric power, a battery of the automobile can be jump started by power from a battery of another automobile or from a battery in a booster device to thereby start the engine.
To boost the battery of the automobile which is of insufficient electric power by power from another battery, the two batteries must be connected through a pair of electric wires. For example, the positive terminal of the depleted battery should be connected to the positive terminal of the boosting battery. The negative terminals of the two batteries should be connected in a corresponding manner.
Making this connection, however, can be very dangerous if the batteries are connected incorrectly. A battery has a small internal resistance, and there is a voltage difference between a battery with sufficient electric power and a battery with insufficient electric power. Current will thus flow between the two batteries as soon as a connection is made. When the two batteries are connected correctly, which means that terminals of corresponding polarities are connected respectively as described above, a large current passes through the electric wires. When the two batteries are connected erroneously, a current which passes through the electric wires is 10 to 20 times larger than the current existing on the electric wires when the batteries are correctly connected. Additionally, incorrect connection may result in one or both of the batteries being short-circuited. Under such conditions, one or both of the batteries may be damaged, and in some cases, an explosion, fire and damage to the vehicle or to a person may result.
Thus, there is a need for a device, which can be used to ensure that the connection of the two batteries is made correctly and in a safe manner. The device should minimize any risk resulting from incorrect connection between the two batteries and from a short-circuit of one or both of the batteries.
The failure of an engine of an automobile to start due to insufficient electric power, in addition to being due to a battery with insufficient power, may also be due to a bad alternator that has failed to replenish the charge on an otherwise good battery. With a bad alternator, even if the battery is replaced, the new battery does not accumulate electric charge, and its charge is soon drained out again. A bad alternator needs to be replaced in order to prevent recurring low battery problems. Detecting a bad alternator, however, is not an easy task to an inexperienced person.
Also, other simple tasks such as checking the air pressure of a tire, checking for freon gas leakage, and inflating a tire to a proper pressure can often be difficult to those without the necessary experience and know-how. It would also be convenient to know the state of the charge of the jump starter battery itself, as well as the state of charge the depleted battery before and after a jump start.
There is therefore a need for a self-contained jump starter system that can be used as a jump starter, tester, and diagnostic system for a vehicle to assist in performing vehicle diagnostics and minor vehicle repairs. There is also a need for a portable, self-contained jump starter system of the above type that is rugged, has a minimum number of components, is user friendly to people who are not experienced with automobiles, provides self-testing and vehicle diagnostics, and is relatively inexpensive so as to be affordable by a large number of consumers.